<!DOCTYPE html>
<html lang='en'>
<head>
    <meta charset='UTF-8'>
    <meta http-equiv='X-UA-Compatible' content='IE=edge'>
    <meta name='viewport' content='width=device-width, initial-scale=1.0'>
    <title>Document</title>
    <script src='../vue.js'></script>
</head>
<body>
    <div id='app'>
        <h1 >{{msg}}</h1>

        <button @click="msg++">累加</button>
        <!-- v-once指令，控制当前的模板或者组件值在初始化阶段渲染一次 -->
        <h2 v-once="">我加啦once：{{msg}}</h2>
    </div>

    <script>
        Vue.config.productionTip = false;

        const vm = new Vue({
            el : '#app',
            data(){
                return {
                    msg : 0
                }
            }
        })
    </script>
</body>
</html>